Improved Acoustic Radiation Force Impulse Imaging Using Split-Focused Ultrasound Transducer With Phase Inversion Technique

Echo decorrelation artifacts decrease the resolution of the acoustic radiation force impulse (ARFI) images. Reducing echo decorrelation requires that the lateral and the elevational beamwidths of the pushing beam are broad compared to the detection beam. In this study, we propose the split-focused ultrasound based on phase inversion technique to achieve this goal. The proposed technique can be implemented with a cross-segmented transducer composed of four rectangular elements driven by signals having different phases. Four independent focal lobes were generated in the lateral and elevational directions, extending the beamwidths in both directions. A finite element analysis (FEA) simulation was conducted to verify the performance of the proposed technique, and an experimental demonstration was performed using the fabricated prototype transducer and a tissue-mimicking gelatin phantom. Compared to the conventional model, the proposed method reduced the jitter by up to 4.7 times at the peak mean displacement, improving the accuracy of the measured displacement, and increased the peak contrast-to-noise ratio by 2.1 times. Thus, the proposed technique can contribute to improve the resolution of the ARFI imaging.